The leaves of oregano contain a wide range of chemicals that may have some effect against bacteria and resistant bacterial strains but there are very few research and no patient trial studies proving its effectiveness in the treatment of acute and/or chronic urinary tract infections.

What is oil of oregano?

The herb oregano (or Holy Basil) is well known for its culinary usage. It belongs to the mint family and is known as the ‘pizza herb’. The leaves are picked from the plant, then steam-distilled to extract the essential oil.

The leaves contain a wide variety of chemical compounds, including leanolic acids, ursolic acids, phenolic glycosides, carvacrol, thymol, cymene, and terpinine. It’s these chemicals that have been proposed to be those with beneficial effects.

Oil of oregano and UTI infections

Wild oregano oil with a high content of carvacrol which has been shown to eradicate Pseudomonas aeruginosa bacteria in a laboratory setting but this study did not address its usage in bacterial infections of the urinary tract or include patient trials.1, 2 Pseudomonas aeruginosa is a common urinary pathogen and the third-leading cause of hospital-acquired UTI.

The chemical compounds within Oil of Oregano, carvacrol and thymol in a laboratory study published in The Journal of Microbiology Research in 2011 have been shown to disintegrate the outer membrane of Pseudomonas. The same study also noted its ability to reduce bacterial adherence to create biofilms in certain Pseudamonas strains although it is far less effective against bacteria already embedded into existing biofilms.

What are the issues around the use of oil of oregano?

  • Controlled trials and studies are often limited in complementary and alternative medicine and involve small numbers of participants. They are often conducted under less rigorous controls, guidelines and environments than those undertaken for the development of new pharmaceutical medications such as antibiotics. Do your research, there should be clear, peer reviewed, empiric evidence as to the efficacy of complementary therapies rather than theorisation about how they may be beneficial in the treatment of a chronic UTI.
  • Although research has been carried out in a laboratory setting using oil of oregano against bacteria and resistant bacterial strains, this research did not include patient studies. A key point to remember if considering its usage.
  • One study from Jordan looked at urinary pathogens and suggested that oregano oil might be helpful for just one urinary pathogen (E. coli) in conjunction with antibiotics but not for the other common urinary pathogens which were tested in the study 3
  • There are no clinical studies looking at the safety profile of oregano or oregano oil. There is obviously a big difference between having a sprinkle of dried oregano on a pizza versus versus ingesting pure oregano oil.

Considering using a complementary medicine? Before doing so it may be worth reading the Buyer Beware information on our Natural Supplements home page.


1 Lambert RJ, Skandamis PN, Coote PJ, Nychas GJ. A study of the minimum inhibitory concentration and mode of action of oregano essential oil, thymol and carvacrol. J Appl Microbiol. 2001;91(3):453‐462. doi:10.1046/j.1365-2672.2001.01428.x

2 Sienkiewicz M, Wasiela M, Głowacka A. Aktywność przeciwbakteryjna olejku oreganowego (Origanum heracleoticum L.) wobec szczepów klinicznych Escherichia coli i Pseudomonas aeruginosa [The antibacterial activity of oregano essential oil (Origanum heracleoticum L.) against clinical strains of Escherichia coli and Pseudomonas aeruginosa]. Med Dosw Mikrobiol. 2012;64(4):297‐307.

3 Darwish RM, Aburjai TA. Effect of ethnomedicinal plants used in folklore medicine in Jordan as antibiotic resistant inhibitors on Escherichia coli. BMC Complement Altern Med. 2010 Feb 28;10:9. doi: 10.1186/1472-6882-10-9. PMID: 20187978; PMCID: PMC2839964.